Largest-ever solar-cell plant makes clean, quiet debut

Each morning when the sun comes up over the snow-capped San Gabriel Mountains here, 108 gigantic ''faces'' are waiting for it in rapt attention like a classroom of earnest students.

This array of solar-cell panels follows the sun's every move from the time its earliest rays peek over the ridge until the last glow disappears from the opposite horizon. The electricity generated by these moving billboards streams into the southern California power system.

The photovoltaic power plant, opened this week by ARCO Solar Inc., is three times the size of any such plant in the world.

Under standard sun conditions here in the high desert northeast of Los Angeles, this plant feeds about one megawatt of electricity into the utility circuits, enough to power some 400 average southern California homes.

What sets a photovoltaic plant like this one apart from other larger solar projects are the solar cells that convert sunlight to electricity.

''It's important to get (photovoltaics) out of the range of watches and calculators and gimmicks and single-panel sales for someone's cabin,'' says Bill Bicker, manager of external affairs for ARCO, expressing the hope of the company that this plant becomes a prototype for much bigger ones.

ARCO Solar is already bidding to build a bigger installation for the Sacramento Metropolitan Utility District. ARCO Solar, a subsidiary of Atlantic Richfield Company, built the plant in six months and estimates it could build one like it in four.

The bid ARCO made to Sacramento officials for the 1.2 megawatt photovoltaic plant was $5.63 per watt of generating capacity.

''This bid represents a breakthrough for the industry,'' since photovoltaic (''PV'') power cost $8-$10 per watt capacity only a year ago, according to Edward C. Kern Jr., director of the Photovoltaic Systems Program at the Massachusetts Institute of Technology.

ARCO hopes to sell either PV power plants or just solar cells to buyers in other areas, including the Mediterranean basin, as well as to the American Southwest.

Two advantages PV power has for the arid Southwest is that it doesn't require cooling water, as do some other kinds of solar power, and it doesn't pollute the air, as do fossil-fuel generators.

Victorville's clear air here at almost 4,000 feet elevation is ideal, engineers at the project say. The photovoltaic process actually works more efficiently at cooler temperatures, and the sun is obstructed here less than 10 percent of the year.

He adds that the plant would not have been financially viable for ARCO if it weren't for government tax credits, which amounted to about one-third of the cost of the plant.

Now that it's built, he says, the plant will cost a pittance to operate.

The unmanned power plant has no moving parts. Only the big, 1,024-square-foot arrays shift patiently, like the hour hand of a clock, to catch the sun with an occasional gasping noise of their tiny motors. Even cleaning is no problem, according to the plant's engineers, since the glass surface is so smooth that a light wind will dust it off.

The expense in building photovoltaic power plants lies in manufacturing the solar cells. Each cell is a brittle wafer of silicon the size of the palm of a man's hand. Silica, the common stuff sand is made of, is melted down and formed into a crystal the size of a stick of firewood. The wafers are then sliced off, polished, and conductors inlaid on them to conduct their charge.

Southern California Edison buys the power the solar cells produce from ARCO Solar at what they call ''avoided cost,'' the cost it would have had to pay to produce the equivalent power in its fossil fuel-fired generators.

The megawatt this plant produces is just a drop in the bucket for the utility , especially during its peak air-conditioning season. But Spencer Carlisle of Southern California Edison says that as photovoltaics, solar thermal, geothermal , and other alternative energy sources become cheaper, more efficient, and more competitive with fossil fuels, ''it will be a very pleasant horse race.''